A three coulor temperature measuring formula has been established on the basis of three primary coulor principle and the plank law. Combined with the digital image processing technology

a method of temperature field measurement and combustion diagnosis for utility boilers has been put forward by using neural networks

and a set of system being designed according to the said method

and practical operation on a 200MW unit being carried out. Results show that the said system to be simple and convenient for practical application

it is possible to realize on line detection of the temperature field

and to evaluate the combustion situation in the furnace in conformity with reality

having a certain value for engineering application.